Environment and Natural Resources Institute, University of Alaska Anchorage, Anchorage, AK, 99508, USA.
Department of Environmental Sciences, University of Toledo, Toledo, OH, 43606, USA.
Nat Commun. 2020 Aug 12;11(1):4024. doi: 10.1038/s41467-020-17790-5.
Soil microbial communities remain active during much of the Arctic winter, despite deeply frozen soils. Overwinter microbial activity affects the global carbon (C) budget, nutrient cycling, and vegetation composition. Microbial respiration is highly temperature sensitive in frozen soils, as liquid water and solute availability decrease rapidly with declining temperature. Climate warming and changes in snowpack are leading to warmer Arctic winter soils. Warmer winter soils are thought to yield greater microbial respiration of available C, greater overwinter CO efflux and greater nutrient availability to plants at thaw. Using field and laboratory observations and experiments, we demonstrate that persistently warm winter soils can lead to labile C starvation and reduced microbial respiration, despite the high C content of most Arctic soils. If winter soils continue to warm, microbial C limitation will reduce expected CO emissions and alter soil nutrient cycling, if not countered by greater labile C inputs.
尽管土壤被深度冻结，但在北极的大部分冬季，土壤微生物群落仍然保持活跃。冬季微生物活动会影响全球碳（C）预算、养分循环和植被组成。在冰冻土壤中，微生物呼吸对温度非常敏感，因为随着温度的下降，液态水和溶质的可用性会迅速下降。气候变暖以及积雪的变化导致北极冬季土壤变暖。人们认为，温暖的冬季土壤会导致更多的可利用 C 的微生物呼吸、更多的冬季 CO 排放以及在融雪时为植物提供更多的养分。通过野外和实验室观测和实验，我们证明，尽管大多数北极土壤的 C 含量很高，但持续温暖的冬季土壤会导致不稳定的 C 饥饿和微生物呼吸减少。如果冬季土壤继续变暖，微生物 C 限制将减少预期的 CO 排放并改变土壤养分循环，如果没有更多的可利用 C 输入来抵消的话。
